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Plant Profiles

The Best Season Ever: Early-flowering Borage in Bloom

No garden can ever have enough blue flowers: there just aren't that many of them. And though spring is the peak season for blues in the garden, there's always room for more, even then. Especially when the plant in question is also a fearless groundcover, a "Wow, what is that?" rarity in North America, and an early-season salad green.

These are the sky-blue flowers of early-flowering borage, Trachystemon orientalis, a woodland groundcover native from the Balkans to the Caucasus.

Unlike the more familiar flowers of its summer-blooming borage relative, Borago officinalis, the sky-blue petals of Trachystemon curl back as they open.

But before they do, pick some of the leaves for the table. Sprays of the flowers are edible, too; both are reported to be very nutritious. The taste is very mild, while the rough texture is all the better than smooth greens at holding a vinaigrette.

Here's how to grow this exceptional groundcover:

Latin Name:

Trachystemon orientalis. Say "track-HISS-te-muhn or-ree-en-TAIL-iss."

Common Name:

Early-flowering borage. Early? When do other borages flower? Borago officinalis is the traditional borage of cottage gardens, and in Zones 5 through 8 it can be in flower from June through August or September: late Spring to late Summer. (In climates where frost is rare, it flowers for much of the year.) For any borage to flower in early Spring really is notable.

Family:

Boraginaceae, the Borage family

What kind of plant is it?

Hardy, spreading, deciduous perennial.

Hardiness:

Most reliable in Zones 6 to 9; hardiness into Zone 5 is possible with supportive siting & culture. See "Where to use it" and "Culture," below.

Habit:

Rhizomatous and outward-bound, Trachystemon orientalis can easily form colonies a yard or two across. Strikingly large heart-shaped leaves on long hairy petioles emerge in loose clusters from the rhizomes to form a weed-suppressing mat. The muscular bulk of the mass of mature foliage will at first remind you of that of a hosta, but Trachystemon leaves arise individually, not in hosta-ish rosettes, which always emerge as tightly furled as spears. Nonetheless, the two are similar in their groundcovering prowess as well as preference for shade: use Trachystemon, then, as if it were a cool spreading hosta.

Rate of growth:

Moderate but insistent: a colony's eventual extent catches up on you. Trachystemon orientalis is not a good choice near anything the same size or smaller. See "Plant partners," below.

Size in ten years:

Up to eighteen inches high and indefinitely wide. Trachystemon is so vigorous and intrepid that it is excellent for naturalizing as well as in controllable settings in the garden.

Texture:

In early spring, when the stalks of flowers are interspersed with still-small emerging foliage, the texture is dappled and particulate. The leaves enlarge dramatically as they mature, crowding together into a dense, heavy, shin-high mass that projects the same "There, that's done" groundcovering authority as a swath of hostas. Avoid a look of squatness or compression by using Trachystemon near and beneath tall plants with soaring stems and, when possible, small or lacy foliage. See "Plant partners," below.

Grown for:

Groundcovering ability that is achieved, for once, by something other than the usual pachysandra, vinca, and hostas. There can never be too many options for plants that grow thickly enough to discourage weeds. The success of Trachystemon isn't due just to its leaves' size or, even, their dense growth: If the leaves were held bolt upright, weeds could still poke up between them. Instead, each leaf angles over just enough to overlap its neighbors. Together, they block the sun with multiple layers of foliage.

Its unusual foliage, which is rough to the touch but not to the eyes. Hosta is the large-leaved groundcover with similar scale and effectiveness, but its leaves are smooth-surfaced (although sometimes deeply puckered), somewhat shiny, and often brightly colored. Trachystemon foliage is as large as that of many a hosta, but is a matte mid-green. The leaves are arrayed one by one throughout the colony, not grouped in hosta-like rosettes.

Its resistance to browsers: Deer will readily nibble smooth and juicy hosta foliage to the ground. Trachystemon petioles are fuzzy and, so, aren't usually touched. The veiny Trachystemon leaves have a non-reflective surface because of very short hairs that aren't easily discernible to the eye, but are sandpapery to the touch. Browsers usually pass the leaf blades by, too.

Its spring flowers: These are more curious than prominent, and are most engaging at close range. White-haired pink petals change to sky blue as they curl open, exposing their white bases as well as a projecting cone of black-anthered stamens surrounding a pale pink pistil. The nodding flowers are massed on loose panicles atop hairy stems that might rise a full foot before branching but, in my experience, are much shorter.

Flowering season:

Early Spring: mid- to late April for me.

Color combinations:

The white, blue, and pink flowers are ephemeral but showy enough that they could converse well with early-spring bulbs in similar hues. The green foliage that follows is neutral in hue but eye-catching in texture. See "Plant partners," below, for combinations that highlight this unusual perennial in spring and summer. In my experience, Trachystemon doesn't display showy fall foliage. Plus, being readily deciduous, it doesn't have a winter presence, either: this is a two-season performer.

Plant partners:

Make your choices first and foremost to ensure maximum vigor and season-long beauty of the colony's foliage, whether or not the early-season floral display is also highlighted. Sun that is strong as well as day-long is tolerated and even appreciated in spring, because temperatures are still cool and moisture comparatively plentiful. That same intensity of sun could scorch the foliage during the hot and droughty months of summer. The ticket, then, is to pair Trachystemon with taller deciduous plants that provide some shade by the time hot weather arrives: this means shrubs and trees usually, but also strongly-erupting perennials and grasses that are short in spring but triumphantly tall in summer.

Trachystemon flowers so early—the same weeks as forsythia—that few such tall shade-providers will also be in flower. Be wary of combining Trachystemon with most that are: like forsythia, their flowers are often in shades of yellow that would clash with the pink, blue, and white of the flowers of Trachystemon. So, avoid siting it near Cornus mas, Hamamelis or, of course, Forsythia itself.

Here are some early-season woodies that avoid yellow even as they bloom at the same time as Trachystemon: Abeliophyllum distichum, some cultivars of Chaenomeles, Lonicera x purpusii 'Winter Beauty', Magnolia stellata, Malus, Prunus, and Pyrus (all variously white or pink), Viburnum x bodnantense and almost any of the hundreds of other deciduous, non-yellow Magnolia species and cultivars (pink), and the PJM group of cultivars of Rhododendron (lavender).

Trachystemon also thrives under large deciduous trees, but the colors of their flowers are likely to be so high overhead as to be irrelevant. So plant Trachystemon under maples, beeches, birches, oaks, and willows of any stripe.

Herbaceous companions to Trachystemon need to be tough enough in three ways to persist: their roots need to be greedy and deep so as not to be out-competed by the mat of roots of Trachystemon. Their emerging stems need to be strong enough and early enough to poke up through the spaghetti of Trachystemon rhizomes, let alone the thick foliage. And, their stems need to mature higher than the Trachystemon foliage lest those stems' leaves be shaded out by summer.

Provided they mature tall enough—eighteen inches would be the minimum—almost any plant whose stems could be called canes could handle growing amid a colony of Trachystemon. These include bamboos, Heracleum, ornamental grasses, and Polygonum. The emerging foliage of some other "non-caning" plants can also can be muscular enough to to thrust up through Trachystemon growth: Think of the croziers of the larger forms of fern, such as Matteuccia and Osmunda, or the thick petioles of almost any form of Petasites, Podophyllum, and Rheum. Hosta is in a class by itself, in that its emerging rosettes of foliage are so tightly furled that they both look and function like spears. Other "spears" to trial include Arisaema and Dracunculus.

Would spring ephemerals succeed? Could their foliage and flowers poke up through the mat of Trachystemon rhizomes, then up through its emerging foliage and flowers? If so, would the foliage be tall enough to receive the full season of sun it needs, regardless of the thick coverage that mature Trachystemon leaves would be making closer to the ground? Remember, also, that it will be difficult to lift, separate, replant, or replace clumps established amid the tangled rhizomatous growth of a colony of Trachystemon.

Which ephemerals, then, are early enough, tall enough, and persistent enough—and might also be blue? Alas, none! Crocus, Iris cristata, Iris reticulata, Muscari, and Scilla aren't tall enough. Iris bucharica and Iris pumila both flower in time, but aren't tall enough; also, Iris bucharica flowers are only available in yellow. Galanthus is too early, Camassia too late. Allium needs full sun and, usually, soil that's drier in summer. Hyacinth needs regular replacing. Most tulips also need replacing (and flower too late), whereas the forms that usually perennialize best—the early-blooming species such as Tulipa greigii and T. kaufmanniana—are too short and usually flower in clashing shades of orange and red. Just as problematic, tulips all want a "good baking" when dormant: lean soil that becomes hot and dry in the required full-sun spots.

Happily, there are plenty of tall-enough Narcissus where neither the petals nor the cups trumpet yellow, orange, or brick red. So, although there are no blue Narcissus, there are forms that are white as well as pink. Both the petals and cups of Mt. Hood are chilly white. There are tall-enough pink Narcissus, too, such as Pink Charm. Another tall-enough, early-enough, persistent-enough, not-needing-division, not-yellow spring bulb is Leucojum aestivum. Its flowers are white.

Especially when Trachystemon is used as the sole groundcover to simple plantings—as would be the case in, say, a courtyard garden in the city—its striking texture would be highlighted by maximizing the contrast of its large rough leaves with the tiny ones of its neighbors. Could a mass planting of Trachystemon be punctuated by topiary of Ilex crenata 'Beehive' or mounds of Taxus baccata 'Amersfoort'? Could it be backed by a wall covered with Hydrangea anomala 'Miranda' or Hedera helix 'Birdsfoot'?

Where to use it in your garden:

Trachystemon is nearly invincible where happy, and can then be so vigorous that it can be used for large-scale coverage in the shade directly beneath deciduous shrubs and trees, as well as amid grasses, perennials, and some ferns that are also large enough to cast shade. In these settings, its comparatively quick-to-emerge foliage catches spring sun and warmth, then tolerates the shade these taller partners cast by summer. See "Plant partners," above.

Trachystemon can also thrive with just the morning sun it would receive on the east sides of buildings, fences, and evergreen shrubs and trees. Note that it might not be able to colonize under the canopies of tall evergreens the way it often will do without hesitation under the canopies of deciduous woodies: evergreen foliage is likely to keep the available sun right under the canopy to below what's needed to sustain Trachystemon year after year.

Ornamental considerations will inform your choices of sites for this species, too. Its large and coarse foliage would be in dramatic contrast to feathery, needly, or grassy leaves of nearby companions. The blue-pink-white flowers in early spring can harmonize with these same colors in the blooms of nearby bulbs, shrubs, and trees—but would clash miserably with the butter yellow of omnipresent forsythia. See "Plant partners," above.

Well-grown colonies of Trachystemon form a strikingly full and dense mat of foliage from late spring through hard frost, so this species could be used as the wall-to-wall filler in formal settings of just a few types of plants arrayed in strict geometry. (Gardeners faced with dressing up the shady courtyard or rear-garden beds of townhouses take note.)

Spring frosts can destroy the early growth, flowers and foliage both. New leaves will emerge to replace the damaged ones, but not new flower stems. Don't let this deter you from using Trachystemon wherever its weed-proof summer foliage would be an asset. But do experiment with establishing a colony or two that would be at reduced risk for such frost "burn." One classic option would be to plant close to a building or even under its eaves (but in the latter case, take care that the colony still receives enough water): cold air is denser than warmer, so falls down onto the landscape from above. The building's radiating warmth repels or at least deflects some of the cold air, while any that does strike the roof slides down its sloping surface and away from the building's foundation just like rain.

Another frost-cheating solution is to plant anywhere on a slope that lets colder air (which, remember, is denser than warmer) slide farther down that slope. Regardless that the slope is fully exposed to the open sky from which that dense and frosty air will descend, if the path is free of blockages such as hedges, fences, or building, that dense air it will slide harmlessly to further down the slope instead of lingering on the colony. True, more cold air will fall from above (or slide down from up-slope), but when frosty air is in motion regardless of its actual temperature, plants are at less risk. Conversely, a colony planted at the bottom of a slope, or where the down-slope is blocked by that fence or hedge or building, or in a dip in level ground, is likely to be "swamped" by the frosty air as it collects, just like rain, in the low spot. With the frigid air then comparatively still, its frost can settle onto the plants with full destructive force.

Culture:

Trachystemon can be a nearly ruthless woodland groundcover where native (see "Native habitat," below). But establishing it in a garden takes careful consideration of its potential sites (see "Where to use it," above) and their ambient conditions.

Yes, this species is likely to succeed when the strength of the sun it receives, the temperature and humidity, and steadily-available moisture are, in sum, within the species' range of viabilities—and that can mean quite a spectrum of situations, from dry shade to moist sun. You'll be wise, though, not to choose extreme circumstances when getting your stock colony going. Increasing soil moisture can balance strong sun or longer intervals of full sun, as long as the moisture isn't a result of poor drainage, which is likely to rot the rhizomes. Conversely, increasingly low soil moisture and humidity are tolerated in cool-summer climates and/or when the exposure to strong sun is lessened due to shade, prevailing cloudiness, or shelter from wind.

Conditions that fall outside this (admittedly) multi-valent range of viability will likely lead to colony disappearance due to rhizome rot, or to scorched foliage due to excessive drought, sun, or wind, or to low humidity.

Established Trachystemon colonies may well extend outward on their own into such less-than-classically-hospitable conditions where de novo plantings would be difficult: into patches of full sun and rocky thin soil, say, or deeper into the dry shade amid the roots of deciduous trees. But to get your first colony started, maximize the chances for success by planting Trachystemon in moisture-retentive but reasonably draining soil. Choose a site where the sun is dappled all day or, if full-on, lasts only until late morning before being blocked from the west by higher plants, buildings, fences, or a rising elevation.

Trachystemon is so serviceable that you can then succumb to temptation by trying to establish divisions in less ideal spots. (See "Propagation," below.) You'll always have a vigorous stock colony in reserve.

How to handle it: The Basics:

Plant divisions or new plants in Spring. Because even small plants can produce full-sized foliage, Trachystemon can quickly become pot-bound at the nursery. These appealingly lush plants will quickly wilt without attentive watering, and can be challenging to sustain until you get them in the ground. I write this from bitter experience.

Trachystemon doesn't need routine maintenance after becoming established within the wide range of supportive conditions detailed in "Culture," above. In my experience, the fading flower stems are swallowed up in the rising tide of the dense, maturing foliage. Colonies don't seem to need division every few years, either: they neither die out at the center nor lose vigor overall. (This is another welcome similarity to hosta.) See below for options on handling the dead fall foliage.

How to handle it: Another option—or two?

After frosts, the thick leaves of Trachystemon turn brown and fall over—but, mostly, remain attached to the rhizomes until spring. While fastidious gardeners may have the time and patience to cut away this dead foliage before winter, there's probably benefit to leaving it in place until early spring. Trachystemon isn't as hardy as everyone could wish—sources often list just to Zone 6—and these stiff, still-attached leaves could help. They'll catch smaller leaves and twigs that are always blowing about the garden as winter approaches, then hold them more or less in place until new growth erupts from below in spring. Better still, the enduring rigidity of the Trachystemon leaves helps keep this naturally-accreting mulch from compacting, ensuring that the nooks and crannies remain filled with air—a notably poor conductor of heat or cold—not solid matter.

When growing Trachystemon in the colder portions of Zone 6, and especially if you're experimenting with establishing it in Zone 5, riff on this species' self-mulching tendencies by sprinkling on some purpose-produced mulch of your own. Before new growth begins to get in the way the next season, scrabble away the whole works; the anchoring leaves usually pull free quickly. For me, this means getting out into the garden—and onto a kneeling pad—by late March.

Quirks and special cases:

Trachystemon is literal proof that there's no accounting for taste. Although its sandpapery foliage and flower stems are typically avoided by four-footed browsers, both are popular spring greens in the cuisines of southeastern European and near-eastern cultures where the species is native. In Istanbul, you might buy spring Trachystemon greens by the pound as we might spinach. Here's an introduction to the culinary possibilities, from a blog whose focus is so quirky—edible plants that are also ornamental—that a neologized new category was necessary: edimentals. Memorably, this is also the title of the blog itself: www.edimentals.com

Downsides:

This species' greatest excitement is its unusually large, thickly growing foliage. The early-Spring flowers are a brief distraction at best. Nonetheless, flowers in early Spring that are not the usual daffodils and forsythia are always welcome, so it's a shame that early thaws can trick those of Trachystemon into emerging, only be destroyed by frost. It isn't realistic to attempt to delay their emergence through protective mulching, especially when this species is used as a wide-spreading groundcover: the flowerstalks seem to snake their way up through mulch. Careful siting could help in-flower colonies escape frost "burn." See "Where to use it," above.

The large foliage doesn't transition to showy fall colors before turning brown and falling over for the winter, but it does remain attached. In my experience, it is persistent enough to interfere with the emerging flower stalks the following spring. On the upside, these attached dead leaves stay rigid enough to provide a bit of self-mulching protection where Trachystemon might not be fully hardy. See the second "How to handle it" box, above, for options for seasonal maintenance.

Variants:

To my knowledge, Trachystemon orientalis is available only as the straight species. Oh, to have a cultivar whose leaves were edged in white. There don't seem to be other species in the Trachystemon genus, either, so it's T. orientalis or bust.

Availability:

Still unaccountably scarce at retailers. Try this online source, as well as this one.

Propagation:

By division in early Spring, before new foliage or flower stalks have emerged.

Native habitat:

Trachystemon orientalis is native from Bulgaria through Turkey into the Caucasus. The species name—orientalis—is a reflection of the West's pre-20th Century worldview, when anywhere from Istanbul to Tokyo could be lumped together as Eastern or Oriental. If the species were being renamed now, more world-wise choices could be, say, caucasium or bulgaricum.